1. Field of the Invention
The present invention relates to a radio telecommunication apparatus for use in a mobile radio communication system, such as cordless telephone, pagers, or a mobile telephones, which transmit an identification code at a transmitting side and which receives said signal at a receiving side for identification.
2. Description of the Related Art
A cordless telephone system comprises a fixed device connected to, for example, a subscriber's line and cordless telephone sets connected in a one-to-one correspondence to the fixed device via a radio channel. In this type of cordless telephone system it is necessary to prevent an error of a connection to other adjacent cordless telephone system. Therefore, an identification code (hereinafter referred to as an ID code) is initially allocated as its own code to the respective system. When it is desired to make a connection between a cordless telephone set and the fixed device, an ID code is transmitted from, for example, a connection-requesting side. The transmitted ID code is received at the receiving side to be compared with those initially stored ID codes for identification. Only when a coincidence occurs between the received ID code and the subscriber's own code, a connection is allowed to be established so that a message channel therebetween is accomplished.
On the other hand, a paging system comprises, for example, a base station and a plurality of pager receivers for receiving a paging signal which is sent from the base station. These pager receivers have their own ID codes allotted thereto. Upon the generation of a call request to any pager receiver, the base station inserts a corresponding ID code into the paging signal and transmits it. Each time the pager receiver receives a paging signal, it compares the ID code of the paging signal with their own initially stored ID codes for identification. If there is a coincidence therebetween, a sound is produced, informing the owner of the pager receiver that there is a call.
A conventional radio telecommunication apparatus for use in such a system includes a control circuit generally having a microcomputer and a separate ID-ROM. The ID code is initially written into the ID-ROM. Upon a transmission or identification of the ID code, the control circuit gains access to the ID-ROM and takes the ID code out of the ID-ROM.
For this reason, for each transmission or comparison of both ID codes, the conventional radio telecommunication apparatus dissipates electric power due to access of the ID-ROM. This offers a problem of a great power dissipation on the apparatus, especially in a system which has a high traffic. If a battery, in particular, is employed as a power source, then there occurs a hastened battery dissipation, a situation which is not very useful.